Background: The need for surgical correction of frontal bossing in patients with sagittal synostosis is currently debated. The authors retrospectively analyzed frontal bossing in patients with isolated, nonsyndromic sagittal synostosis who underwent calvarial remodeling with and without frontal craniotomy and compared with control subjects.
Methods: The authors analyzed computed tomography (CT) scans of patients with sagittal synostosis <9 months of age (6.2 ± 1.6 months) who underwent modified-pi procedure either with frontal craniotomy (FC, n = 15) or without frontal craniotomy (NFC, n = 10). Only patients treated with both pre-operative and 1-year post-operative CT scans were included. Non-synostotic age-matched control scans were also analyzed. Cephalic index (CI), 3 previously validated measures of frontal bossing (bossing angle, horizontal bossing ratio, and vertical bossing ratio), and pre-nasion volume ratio were obtained. Additionally, three-dimensional photographs of 10 FC patients were evaluated for frontal bossing between 1 and 8 years post-operatively.
Results: Pre-operatively, no significant differences were found between the 2 groups (.064<P < 0.940). Both groups showed greater scaphocephaly and frontal bossing compared to controls (P < 0.001). One-year post-operatively, all measures improved but remained significantly different than normal values except: CI of NFC patients (P = 0.296); bossing angle (P = 0.068) and horizontal bossing ratio (P = 0.129) of FC patients. Compared to NFC patients, horizontal bossing ratio was significantly improved in FC patients (P = 0.017, mean difference of 0.047). No other statistically significant differences were found between the 2 techniques (0.127<P < 0.637).In our long-term study of FC patients up to 9 years of age (n = 10), the authors analyzed forehead inclination as our measure of frontal bossing in three-dimensional photographs. A linear regression analysis showed a significant reduction in forehead inclination with age, decreasing 1.3 ± 0.4 degrees per year (P = 0.021). Forehead inclination for controls did not change significantly with age (P = 0.558).
Conclusions: At 1-year following modified-pi procedure, FC patients approached normalization of their forehead morphology to a greater extent than NFC patients. However, neither group completely normalized during this time period. Frontal bossing in FC patients continued to decrease with age, which reveals the post-operative dynamic nature of frontal bone morphology during childhood for these patients.